I think it's definitely beneficial for these characters to have good acting voices behind them and it affects the characters in a way that people can feel like they're part of the game and that they know these characters.
There's a lot more to see when you're playing and because of the advances in technology it makes room for all kinds of new characters.
I think there are more female characters in videogames now but I also think that's because videogames in general are more diverse now.
Start as early as you can. Make tapes of your characters.